The invention relates to methods in reeling a paper web and to reel-up apparatus.
In the terminal end of a paper machine or finishing apparatus for paper, a paper web of several meters in width which is produced and/or treated at preceding machine sections, is reeled around a reel spool to form a machine reel. In this reeling up process a reeling cylinder that is arranged rotatable is typically used for guiding the paper web onto the machine reel, wherein the nip contact between the reeling cylinder and the machine reel is utilized to affect the quality of the reel produced thereby. A conventional solution is the one in which the reeling cylinder remains in its place and the reel spool around which the reel is accumulated in nip contact is moved during reeling on the supporting structure, for example by supporting the ends of the reel spool on reeling rails. The ends of the reel spool are acted upon with a suitable loading mechanism to adjust the nip contact between the machine reel that is being formed and the reeling cylinder. Such reeling concepts and loading methods related thereto are disclosed for example in the Finnish patent 91383 and in the corresponding U.S. Pat. No. 5,251,835, as well as in the Finnish patent application 950274 and in the corresponding U.S. Pat. No. 5,690,298.
Another known solution is the one in which the reeling cylinder is arranged to move on a carriage, and the machine reel is rotated with a centre drive in a stationary reeling station, i.e. the centre of the reel spool remains at the same location. When the diameter of the machine reel is increased, the reeling cylinder is displaced in such a manner that the carriage supporting the same moves along a guide. Such an arrangement is known for example from the European application publication 792829 and in the corresponding U.S. Pat. No. 5,988,557.
The U.S. Pat. No. 5,370,327 discloses a solution in which the reeling cylinder moves in the vertical direction, thus enabling the maintaining of the angular position of the nip between the reeling cylinder and the machine reel constant when the reel moves on reeling rails. The low position of the reeling cylinder and the movement of the same in the vertical direction enable the transfer of the reel spools from a storage to a reeling station along a straight transfer path. The solution contains two pairs of reeling carriages, of which the pair that has delivered a full machine reel can return to fetch a new empty reel spool past the other pair guiding the reel to be reeled. A corresponding reel-up containing a stationary reeling cylinder in a low position and a reeling station moving by means of carriages, is known from the U.S. Pat. No. 5,673,870. Both solutions contain a drive motor moving along rails together with the movement of the respective pair of carriages on both sides of the reel-up, said drive motor being coupled to a reel spool located in the pair of carriages.
In addition to the stationary reeling cylinder that guides the web on the reel, according to the Finnish patent application 950274 and the corresponding U.S. Pat. No. 5,690,298, it is possible to use an auxiliary roll located at a lower position and moving in the vertical direction, said auxiliary roll forming a second nip with the machine reel formed in the moving reeling station. Before the change this auxiliary roll is in contact with the reel that is becoming full, which has been driven off the reeling cylinder. A corresponding arrangement in connection with a change is disclosed in the Finnish patent 91383/U.S. Pat. No. 5,251,835.
The aim is to obtain constantly larger machine reels to minimize reel changes. At present, machine reels are generally rotated with a centre drive, i.e. the end of the reel spool is connected to the drive motor with a suitable transmission mechanism. In primary reeling in which a new reel spool is brought in contact with the paper web travelling via the reeling cylinder, the reel spool is rotated with the center drive of the initial reeling device to accelerate the reel spool to the web speed and to form the bottom layers of the reel after the cutting and change of the web. The initial reeling device (which, according to the aforementioned U.S. Pat. Nos. 5,251,835 and 5,690,298, can be a pair of swinging arms pivotable in the vertical plane, or according to the U.S. Pat. Nos. 5,370,327 and 5,673,870 always one of the pair of carriages) is always accompanied by a drive motor of its own, and another drive motor moves along with a transfer device, such as reeling carriages, which are in contact with the ends of the reel spool during final reeling.